open access

https://hdl.handle.net/2115/75582

Neutron crystallographic study of heterotrimeric glutamine amidotransferase CAB

英語

neutron diffraction

2019-03

International Union of Crystallography

Acta crystallographica Section F

75

193-196

Heterotrimeric glutamine amidotransferase CAB (GatCAB) possesses an ammonia-self-sufficient mechanism in which ammonia is produced and used in the inner complex by GatA and GatB, respectively. The X-ray structure of GatCAB revealed that the two identified active sites of GatA and GatB are markedly distant, but are connected in the complex by a channel of 30 angstrom in length. In order to clarify whether ammonia is transferred through this channel in GatCAB by visualizing ammonia, neutron diffraction studies are indispensable. Here, GatCAB crystals were grown to approximate dimensions of 2.8 x 0.8 x 0.8 mm (a volume of 1.8 mm 3) with the aid of a polymer using microseeding and macroseeding processes. Monochromatic neutron diffraction data were collected using the neutron single-crystal diffractometer BIODIFF at the Heinz Maier-Leibnitz Zentrum, Germany. The GatCAB crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 74.6, b = 94.5, c = 182.5 angstrom and with one GatCAB complex (molecular mass 119 kDa) in the asymmetric unit. This study represented a challenge in current neutron diffraction technology.

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